Device for fixing a fan-blade assembly onto a motor shaft

ABSTRACT

Device for fixing a fan-blade assembly onto a motor shaft The invention relates to a device for fixing a fan-blade assembly ( 10 ) onto a shaft ( 12 ) suitable for being driven in rotation by a motor ( 14 ). It comprises a drive hub ( 24 ) integral with the shaft ( 12 ) and suitable for serving as a support for a hub ( 16 ) of the blade assembly ( 10 ), as well as a stop ring ( 26 ) slipped on around the shaft and equipped with elastic recall means ( 44 ), so as to press the hub ( 16 ) of the fan assembly ( 10 ) elastically against the drive hub ( 24 ). Application especially to the equipment of motor vehicles.

FIELD OF THE INVENTION

[0001] The invention relates to a device for fixing a fan-blade assemblyonto a shaft suitable for being driven in rotation by a motor.

BACKGROUND OF THE INVENTION

[0002] A fixing device of this type finds a particular application tothe equipment of motor vehicles, and especially to the fixing of a bladeassembly of a motor-driven fan unit.

[0003] Such a unit makes it possible to accelerate the speed of anairflow which, for example, passes through the radiator serving forcooling a motor-vehicle engine.

[0004] Such a fan assembly, also called turbine, usually comprises ahub, also called “bowl”, from which arise a plurality of blades whichextend radially outwards. These blades have outer extremities which areeither free, or preferably joined together by a profiled ring, alsocalled “shroud”.

[0005] Such a fan assembly is generally produced by moulding fromplastic, for example from loaded polyamide, and it is fixed onto themotor shaft by fixing means of the nut-and-bolt type with theinterposition of an elastic coupling produced in the form of a ring madeof elastomer material or the like.

[0006] These known fixing means, however, have the drawback of notsufficiently reducing the parasitic imbalance phenomena which arise whenthe centre of gravity of the fan assembly is not on the rotational axisof the motor shaft.

[0007] These imbalance phenomena stem essentially from the rigidity andfrom the geometry of the link between the blade assembly and the motorshaft.

[0008] In particular, it has been observed that the ring made ofelastomer material has a tendency to age over time and to lose itselastic properties.

[0009] This results in high levels of imbalance which generate vibrationat given rotational frequencies, as well as giving rise to a reductionin the reliability of the moving parts.

[0010] Furthermore, these known fixing devices have the drawback ofrequiring tooling for fixing the blade assembly, which complicatesassembly and manufacturing.

[0011] The object of the invention is especially to surmount theabovementioned drawbacks.

[0012] The invention aims, in particular, to obtain a device for fixinga blade assembly onto a motor shaft which makes it possible to eliminatevibration of the blade assembly by reducing the levels of imbalance.

[0013] The invention also aims to obtain a fixing device of this typewhich retains its properties over time.

[0014] It also aims to obtain such a fixing device which enableseffective and rapid fixing of the blade assembly onto the motor shaft,without requiring special tooling.

SUMMARY OF THE INVENTION

[0015] To that end, the invention proposes a device for fixing afan-blade assembly onto a motor shaft, which comprises a drive hubintegral with the shaft and suitable for serving as a support for a hubof the blade assembly, as well as a stop ring slipped on around theshaft and equipped with elastic recall means, so as to press the hub ofthe fan assembly elastically against the drive hub.

[0016] It results therefrom that the blade assembly is assembled andheld axially by a stop ring endowed with elastic properties, and by wayof a drive hub which is integral with the shaft of the motor.

[0017] While the blade assembly is rotating, and under the dynamiceffects transmitted to the structure of the blade assembly, the stopring, because of its elastic properties, deforms and takes up theforces, which makes it possible to realign the main inertial axis of theblade assembly onto the main inertial axis of the motor shaft.

[0018] According to another characteristic of the invention, the drivehub is fixed rigidly onto the shaft.

[0019] Advantageously, the drive hub is suitable for being inserted atleast partly into the hub of the blade assembly so as to make themintegral in rotation via a shape-interlocking link.

[0020] In one advantageous embodiment of the invention, the drive hubcomprises sectors which are offset at angles and suitable for beinginserted into matching-shaped recesses which the hub of the bladeassembly includes.

[0021] According to another characteristic of the invention, the elasticmeans for recall of the stop ring are suitable for being engaged in agroove of the shaft.

[0022] These elastic recall means advantageously comprise elastictongues extending radially within a central aperture of the stop ring.

[0023] These elastic tongues are advantageously of generally biconicalshape. In one preferred embodiment, these elastic tongues are spaced atangles and present in numbers of greater than five.

[0024] Advantageously, the stop ring is produced in a single piece froman elastically deformable material, in particular from spring steel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In the description which follows, given solely by way of example,reference is made to the attached drawings, on which:

[0026]FIG. 1 is a partial view in axial section of a blade assemblyfixed onto a shaft of an electric motor by way of a fixing deviceaccording to the invention;

[0027]FIG. 2 is a partial view in exploded section showing a fixingdevice according to the invention combined with a hub of a bladeassembly;

[0028] FIGS. 3 to 5 show various phases of fitting by pushing the stopring onto the motor shaft;

[0029]FIG. 6 is a partial view in perspective corresponding to FIG. 2showing the device in assembled position; and

[0030] FIGS. 7 to 12 are front views of different types of stop ringswhich can be used in the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Referring first of all to FIG. 1, a blade assembly 10 is shown(represented partially), fixed onto a shaft 12 of an electric motor 14,which is driven in rotation about an axis X-X.

[0032] In one preferred application, this blade assembly 10 forms partof a motor-driven fan unit intended to be placed in proximity to aradiator for cooling a motor-vehicle engine in order to increase thespeed of an airflow which passes through this radiator.

[0033] The blade assembly 10 comprises a hub 16, also called “bowl”,from which a multiplicity of blades 18 arise radially, the outerextremities (not represented) of which are either free, or preferablyjoined together by a shaped ring, also called “shroud”.

[0034] The hub 16 of the blade assembly includes a central aperture 20of generally circular shape which is traversed by the motor shaft 12,the latter having one extremity 22 which protrudes outwards with respectto the hub 16 of the blade assembly.

[0035] The blade assembly 10 is fixed onto the extremity of the motorshaft 12 by a fixing device according to the invention, which consistsessentially of a drive hub 24 and of a stop ring 26.

[0036] The drive hub 24 is fixed rigidly onto the motor shaft 12 byappropriate mechanical means. It comprises a cylindrical barrel (FIGS. 1and 2) capable of being pushed axially around the shaft 12 and of beingsecured to it in translation and in rotation by appropriate mechanicalmeans, for example via a splined link.

[0037] This drive hub is advantageously produced from steel and itcomprises from two to eight sectors 30 which extend radially outwardsfrom the barrel 28. These sectors are three in number and are offset atangles of 120° in the example represented in FIG. 2. These sectors,which form lobes or lugs, are each formed with a gap 32 in order tolighten the drive hub 24 and reduce its moment of inertia.

[0038] The hub 16 of the blade assembly, on its inner face 34, turnedtowards the motor, includes recesses 36 suitable for allowing thesectors 30 of the drive hub to be embedded. The recesses 36 and thesectors 30 have matching shapes in order to allow a shape-interlockinglink. Thus, when the drive hub 24 is embedded into the inner face 34 ofthe hub 16 of the blade assembly, a shape-interlocking link is producedwhich secures the blade assembly 10 in rotation on the drive hub 24 and,consequently, on the hub 12 of the motor.

[0039] The stop ring 26 contributes to the assembling and axialretention of the blade assembly by way of the drive hub 24. This stopring 26 is formed by stamping and cutting-out a component formed in amaterial endowed with elastic properties. A spring-steel component isadvantageously used for this purpose.

[0040] The stop ring 26 (FIGS. 1 and 2) comprises a substantially flatannular part 38 surrounded by a collar 40 and delimiting a centralaperture 42 for the extremity 22 of the shaft 12 to pass through. Thering 26 is cut out in such a way as to define a plurality of elastictongues 44 which extend radially inwards into the central aperture 42.These elastic tongues are seven in number in the embodiment of FIG. 2.They each have a generally biconical shape, that is to say they possessan outer part 46 attached to the annular part 38 forming an angle whichis slightly inclined with respect to the plane of this annular part.This angle generally lies between 5 and 40°. From the outer part 46 aninner part 48 or extremity extends (FIG. 1), which is much moreinclined. The elastic tongues 44 define catches the ends of which arefolded and intended to interact with a groove 50 machined on theperiphery of the motor shaft 12, near its extremity 22 (FIGS. 1 and 2).

[0041] The annular part 38 preferably includes at least two gaps 54(FIG. 2).

[0042] Various phases of pushing the stop ring 26 onto the extremity ofthe shaft 12 will now be described, by reference to FIGS. 3 to 5.

[0043] As shown in FIG. 3, the ring 26 is presented facing the extremity22 of the motor shaft. The inner parts 48 of the tongues 44 of the ringdefine a circular passage having a diameter d which is less than thediameter D of the shaft 12. The extremity 22 of the shaft 12 is roundedand then opens out into the groove 50. By exerting pressure on the ring26, in the direction of the arrow F, the inner parts 48 of the tonguesare progressively displaced towards the groove (FIG. 4) and thenpenetrate into this groove, as shown in FIG. 5. In this position, theinner parts 48 form catches which come to interact with a shoulder 52 ofthe groove, in order to form an anti-return lock.

[0044] It results therefrom that the blade assembly is thus assembledand held axially by the stop ring 26, via the drive hub 24. Thuscentring of the blade assembly is achieved, which is obtained by a shortcentring lying between 1 and 4 mm, formed by the lobe-shaped sectors 30,on the drive hub. In this way, the blade assembly can be made to fitwith practically zero clearance with respect to the motor shaft, andwith an axial force which is generally less than 10 kg.

[0045] This results in optimised centring which makes it possibleconsiderably to reduce the static imbalance of the blade assembly. Thestop ring allows axial stopping of the blade assembly by virtue of theelastic tongues 44 which come to lodge in the groove 50.

[0046] When the blade assembly is rotating, and under the dynamiceffects transmitted to the structure of the blade assembly, the elastictongues 44 are deformed and take up the forces, thus making it possibleto realign the main inertial axis of the blade assembly onto the maininertial axis of the motor shaft.

[0047] This stop ring further presents the advantage of being able to bepushed on easily without requiring special tooling, which facilitatesfitting and assembling of the blade assembly on production lines.

[0048]FIG. 6 shows the hub of the blade assembly thus fixed onto themotor shaft by way of the device of the invention.

[0049] It will be understood that the drive hub is susceptible of manyvariants, as long as it is fixed rigidly onto the shaft and as long asit makes it possible to form a support with interlocking shapes with thehub of the blade assembly.

[0050] The stop ring is equally susceptible of numerous embodimentvariants, as long as it includes elastic recall means suitable forinteracting with the groove of the shaft of the motor.

[0051] This stop ring is preferably made from spring steel, but it couldbe formed from another material, including a plastic, endowed withelastic properties.

[0052] It is preferable for the number of elastic tongues to lie betweenfive and nine.

[0053] FIGS. 7 to 12 show various embodiments of the stop ring.

[0054] In the case of FIG. 7, the stop ring includes eight elastictongues 44 and two diametrally opposed gaps 54.

[0055] In the embodiment of FIG. 8, the stop ring also includes eightelastic tongues, but four gaps 54 spaced at angles of 90°.

[0056] The stop ring of FIG. 9 comprises nine elastic tongues 44 andfour gaps 54 spaced at angles of 90°.

[0057] The stop ring of FIG. 10 comprises eight elastic tongues and fourbosses 56 spaced at angles of 90°.

[0058] The stop ring of FIG. 11 comprises eight elastic tongues 44 whichare much shorter than in the preceding embodiments, as well as twodiametrally opposed gaps 54.

[0059] Finally, the stop ring of FIG. 12 comprises five elastic tongues44 and four gaps 54 spaced at angles of 90°.

[0060] The invention finds a particular application to the fixing of ablade assembly of a motor-driven fan unit for a motor vehicle.

[0061] The invention is not limited to the embodiments described by wayof example and extends to other variants.

[0062] Provision can especially be made for the stop ring 26 to becoated wholly or partly with a vibration-absorbing material, such as anelastomer.

[0063] Moreover, provision can be made for an elastomer ring to beinterposed between the hub of the blade assembly 16 and the drive hub 24in order to absorb vibration.

1. Device for fixing a fan-blade assembly onto a shaft suitable forbeing driven in rotation by a motor, characterised in that it comprisesa drive hub (24) integral with the shaft (12) and suitable for servingas a support for a hub (16) of the blade assembly (10), as well as astop ring (26) slipped on around the shaft and equipped with elasticrecall means (44), so as to press the hub (16) of the fan assembly (10)elastically against the drive hub (24).
 2. Device according to claim 1,characterised in that the drive hub (24) is fixed rigidly onto the shaft(12).
 3. Device according to claim 1, characterised in that the drivehub (24) is suitable for being inserted at least partly into the hub(16) of the blade assembly so as to make them integral in rotation via ashape-interlocking link.
 4. Device according to claim 3, characterisedin that the drive hub (24) comprises lobes or sectors (30) which areoffset at angles and suitable for being inserted into matching-shapedrecesses (36) which the hub of the blade assembly includes.
 5. Deviceaccording to claim 1, characterised in that the elastic means (44) forrecall of the stop ring are suitable for being engaged in a groove (50)of the shaft.
 6. Device according to claim 1, characterised in that theelastic means for recall of the stop ring (26) comprise elastic tongues(44) extending radially within a central aperture (42) of the stop ring.7. Device according to claim 6, characterised in that the elastictongues (44) are of generally biconical shape.
 8. Device according toclaim 6, characterised in that the elastic tongues (44) are spaced atangles and present in numbers of greater than five.
 9. Device accordingto claim 1, characterised in that the stop ring (26) is produced in asingle piece from an elastically deformable material, in particular fromspring steel.
 10. Device according to claim 1, characterised in that thestop ring (26) is coated wholly or partly with a vibration-absorbingmaterial.